Just then Joe had an inspiration.

“Bob,” he shouted, “there’s that passageway from the old factory that leads right to the back of the store. Perhaps we can get in from that. What do you say?”

In a flash, Bob remembered. He tore himself loose from Mr. Talley’s grasp and was off after Joe, running like a deer.

And while the boys are frantically seizing this chance of rescue, it may be well for the benefit of those who have not read the preceding volumes of this series to tell briefly who the Radio Boys were and what had been their adventures up to the time this story opens.

Bob Layton, who at this time was about sixteen years old, had been born and brought up in Clintonia, a wide-awake, thriving town with a population of over ten thousand. It was pleasantly located on a little stream called the Shagary River, less than a hundred miles from New York City. Bob’s father was a leading citizen of the town and a prosperous druggist and chemist. No one in the town was more highly respected, and although not rich, he had achieved a comfortable competence.

Bob was a general favorite with the people of the town because of his sunny temperament and his straightforward, manly character. He was tall, sinewy, of dark complexion and a leader among the young fellows of his own age in all athletic sports, especially in baseball and football. On the school nine and eleven he was a pillar of strength, cool, resourceful and determined. His courage was often tested and never failed to meet the test. He never looked for trouble, but never dodged it when it came.

His closest friend was Joe Atwood, whose father was a prominent physician of Clintonia. Joe was of fair complexion, with merry blue eyes that were usually full of laughter. They could flash ominously on occasion, however, for Joe’s temper was of the hair-trigger variety and sometimes got him into trouble. He seldom needed a spur, but more than once a brake was applied by Bob, who had much more coolness and self-control. The pair got on excellently together and were almost inseparable.

Closely allied to this pair of friends were two other boys, slightly younger but near enough to their ages to make congenial comrades. One of these was Herb Fennington, whose father kept the largest general store in town. Herb was a jolly likeable young fellow, none too fond of hard work, but full of jokes and conundrums that he was always ready to spring on the slightest encouragement and often without any encouragement at all.

The fourth member of the group was Jimmy Plummer, whose father was a carpenter and contractor. Nature never intended Jimmy for an athlete, for he was chunky and fat and especially fond of the good things of life; so much so in fact that he went by the nickname of “Doughnuts” because of his liking for that delectable product. He was rollicking and good-natured, and the other boys were strongly attached to him.

They would have been warm friends under any circumstances, but they were drawn still more closely together because of their common interest in the science of radio. The enthusiasm that swept the country when the marvels of the new science became known caught them in its grip and made them the most ardent of radio “fans.” They absorbed anything they could hear or read on the subject, and almost all their spare time was spent in delving into the mysteries of this miracle of modern days.